Detachable deep-viewing coaxial illuminator for flashlights with companion telescopic magnifier

ABSTRACT

A deep-viewing coaxial illuminator accessory that may be easily reversibly attached to commercial high-brightness, focusable-beam flashlights to provide shadow-free viewing of subject matter up to 20 ft or more away is disclosed. 
     A miniature companion telescopic magnifier for optional use with the coaxial illuminator that provides erect-image magnified viewing and may be easily reversibly attached to the illuminator is described.

BACKGROUND Field of Invention

This invention describes a detachable, deep-viewing coaxial illuminator accessory for commercial focusable-beam flashlights that provides shadow-free viewing of subject matter up to 20 feet or more away from the illuminator. My invention may be used to clearly view inside automobile engines and other equipment through small holes or vent openings, behind walls through small openings, and through long vent and plumbing pipes.

A miniature companion telescopic magnifier that reversibly attaches to the eyepiece of this deep-viewing coaxial illuminator and provides magnified non-inverted viewing of objects and sharply focuses over the distance range of the illuminator is also described. The least expensive embodiments of my inventions are suited for use by the general public, auto mechanics, construction workers, and those involved in technical and scientific work.

Description of Prior Art

Devices that permit clear viewing into recesses are currently expensive fiber optic electronic imagers that sell for hundreds of dollars each, and are typically limited by the short fiber optics cable to viewing objects up to a few feet away. Their high cost prevents use by the general public.

This invention is made practical by the development of modern high-brightness, focusable-beam flashlights. My deep-viewing coaxial illuminator has a different optical design from that described in U.S. Pat. No. 5,848,835 which is limited to viewing objects only 1 foot away. This new optical design uses a reflective mirror with a center hole for viewing through, instead of the “beam splitter” described in the previous patent. The mirror provides enhanced flashlight illumination at large distances from the illuminator, and eliminates the slight glare from the flashlight from the beam splitter that degrades viewing contrast of far-away objects. Other commercial designs described in U.S. Pat. Nos. 5,220,453 and 6,985,287 are not suitable for use as a detachable accessory for a flashlight.

Objects and Advantages

My invention has the following advantages over prior art—

-   -   (a) It provides true coaxial-illumination and shadow-free         viewing of objects up to 20 feet away using illumination from         commercial high-brightness, focusable-beam flashlights.     -   (b) It may be manufactured at a fraction of the cost of         currently available electronic imagers, so the general public         can benefit.     -   (c) Because it is a conveniently detachable flashlight         accessory, the owner's flashlight may be used as an ordinary         flashlight with this accessory removed.     -   (d) An optional companion telescopic magnifier (described here)         may be easily attached to provide image-erect, magnified viewing         thru the coaxial illuminator.

DRAWINGS—FIGURES

FIG. 1 and FIG. 2 show a cross-sectional view and a 3-D view, respectively, of the preferred embodiment of my deep-viewing coaxial illuminator.

Reference Numbers in the drawings, dimensions are for preferred embodiment.

-   8 Light from flashlight 20 O-ring, 1 in ID, 1/16 in thick -   10 Opaque housing, 1¾″ L, 1¼″OD, 1″ID 21 Flashlight stop -   12 Eyepiece Body, 1⅜″ L, ¾″ OD, 13 mmID 22 ¼″ ID plastic end cap -   14 Clear window or lens means, ½″ DIA 23 Working distance -   15 Light reflected from subject surface 28 ¾ in hole in housing -   16 Plastic retainer rings, 13 mmOD, ⅜″ ID 30 Subject surface -   18 Mirror with oval hole (32) at center 31 5/16 in ID hollow viewing     tube

DETAILED DESCRIPTION—FIGS. 1 AND 2

The preferred embodiment of my detachable, deep-viewing coaxial illuminator viewing accessory is for use with a 2 AA-cell focusable-beam, high-intensity flashlight such as a Mini-Maglite, and is shown in FIGS. 1 and 2. However, it may also be used with other suitable types of bright collimated light sources to view into deep recesses. It consists of an opaque plastic housing 10 into which an opaque plastic eyepiece body 12 is built. Other suitable opaque materials may be used for the housing and eyepiece body.

The eyepiece body 12 may contain a clear window 14 at the top, or a lens or lens system to provide magnification instead of a window. Alternately, an external lens or lens system (such as the companion telescopic magnifier) may be placed over the window. The window 14 is held in place between two plastic retaining rings, but O-rings, or a set screw, a groove in the eyepiece wall, or cement may be used to hold it in place. An eye cup may attach to the eyepiece to shield high ambient light.

The eyepiece body 12 is cut at a 45 degree angle on the bottom end inside of the housing 10 as shown in the figures, and an oval-shaped mirror 18 is bonded to it with cement. The mirror has a center oval viewing hole 32, whose edge supports the viewing tube 31 that shields light directly from the flashlight from entering the viewing field. The top end of the viewing tube attaches to the lower window retaining ring. The bottom edge of the viewing tube 31 is cut off at a 45-degree angle and is oriented to shield light from the flashlight from producing glare in the viewing field that would spoil visual contrast of distant objects.

A flashlight fits into the left side of opaque housing 10 in FIGS. 1 and 2, and is held in place by lubricated O-ring 20 seated in a groove, but other suitable attachment methods for the flashlight may be used including a thumbscrew, flexible, or snug fitting housing. Plastic end cap 22 covers the end of the housing opposite the flashlight to exclude stray light and dust. Hole 28 in the housing 10 directly below the mirror passes the flashlight illumination to the subject surface 30 below, and the reflected light from the subject surface up to the eye of the observer.

Operation—FIGS. 1 and 2

The flashlight is inserted into the left side of the opaque housing 10 shown in the figures, and is snugly held in place by the O-ring 20, which accommodates small variations in the size of both the flashlight body and opaque housing due to manufacturing tolerances. A small amount of grease on the O-ring aids insertion and removal of the flashlight which is simply pushed into and pulled out of the housing. An optional small step 21 in the inner wall of the housing acts as a stop for the flashlight, which will be unnecessary if the flashlight has a lip on its outer surface that prevents it from being inserted too far. The flashlight beam is focused (by adjusting the flashlight) for the smallest spot size on the subject matter 30. Light from the flashlight 8 enters the housing 10, and is reflected off of the diagonal mirror 18 downward through the exit hole 28 in the housing to illuminate the subject matter 30. The viewer's eye looks down through the clear window (or magnifying lens) 14 through the hollow viewing tube 31 inside the eyepiece body 12 and the hole in the housing 28 to view the illuminated subject matter. The inside diameter may be chosen to optimize viewing into holes and openings of various sizes.

The preferred embodiment of my deep-viewing coaxial illuminator uses a 2-AA cell incandescent focusable-beam flashlight that provides clear unmagnified viewing of high-contrast (eg., black and white) objects at a distance up to 6 feet.

The illumination is exactly coaxial with the viewing axis, which permits shadow-free viewing into cavities, holes, and pipes.

A small external mirror mounted below the bottom opening 28 of the magnifier at 45 degrees with respect to the viewing axis may be used to provide convenient right-angle viewing of objects.

Companion Telescopic Magnifier for Deep—Viewing Coaxial Illuminator Background—Description of Prior Art

This is a miniature non-inverting telescope that quickly and easily attaches to the deep-viewing coaxial illuminator eyepiece to provide erect-image viewing of objects up to at least 20 ft away. Its use with the coaxial illuminator is optional.

Available non-inverting (terrestrial) telescopes with all-glass optics are too expensive, bulky, and heavy to use as an attachment to the light-weight coaxial illuminator flashlight accessory described, and are optically designed to focus on distant objects (10 ft to infinity).

The preferred embodiment of my magnifier that is used with 2-AA cell flashlights sharply focus on objects from 6 ft to ½ ft distant, and provides magnification of 3× to 5× respectively, over this distance range. Magnification is somewhat higher at small object distances due to the optical configuration of this telescopic magnifier.

Objects and Advantages

My invention has the following advantages over prior art—

-   -   (a) It features economic, light weight, compact construction and         it easily attaches securely to the coaxial illuminator eyepiece.         It is easily removable.     -   (b) It provides non-inverted viewing of objects, and the focus         may be easily adjusted over the distance range of the         illuminator. A distance scale on the telescope eyepiece allows         presetting the focus to the estimated distance before viewing.     -   (c) It is constructed of mostly plastic and paper parts, which         may be injection molded or stamped inexpensively in large         quantities.

DRAWINGS—FIGURES

FIG. 3 shows a cross sectional view of my telescopic magnifier.

Reference Numbers in the Drawings, dimensions are for preferred embodiment

-   1 Eyepiece housing 8 Objective lens mount -   2 Objective housing 9 Lens glare stop -   3 Eyepiece lens (10 mm dia, −11 mm FL) 10 Thumbscrew -   4 Eyepiece lens retainers 11 Dowel pin -   5 Lens cushion 12 Dowel pin slot -   6 Objective lenses (0.5 in dia, 2.69 in FL) 13 Objective housing top     edge -   7 Objective lens retainers

Description of FIG. 3

The preferred embodiment of my telescopic magnifier is optimized to provide 3× to 5× magnification, and can focus on objects over the 6 ft to ½ ft range, respectively.

The telescopic magnifier body consists of two opaque telescoping plastic housings. The objective housing 2 holds the objective lens means 6, and attaches to the illuminator eyepiece with a thumbscrew 10. The objective lens means is a positive lens which may be a single element lens or a multiple element lens. The lens retaining rings and lens fit snugly into the lens mount that in turn fits snugly inside the objective housing. An opaque black paper aperture placed between the lenses functions as a glare stop. The end of the housing below the thumbscrew is rounded and contoured to fit snugly over the illuminator body.

The eyepiece housing 1 holds the eyepiece, or ocular, lens 3 means and slides snugly into the objective housing. The eyepiece lens means is a negative lens, but may have more than one element. A lens cushion 5 holds the lens means snugly in place between the two plastic retaining rings 4.

A slot in the side of the eyepiece housing fits a dowel pin in the objective housing so the eyepiece may be focused with a purely up-down motion and limits the adjustment range. A distance scale printed on the eyepiece housing allows presetting the magnifier focus to a known distance.

The lenses and housings form a “Galilean” telescope configuration that provides erect-image (non-Inverted) viewing. Although it has a narrow field of view, it is intended for viewing into holes so is not a limitation for this application. The magnification varies somewhat with focus distance due to the short distances involved. The lens focal lengths and diameters are chosen so the telescope body (eyepiece housing plus objective housing) is suitably very short and small for use as a flashlight accessory.

Operation—FIGS. 1-4

Prior to attaching the telescopic magnifier to the illuminator, the object is first viewed through the eyepiece window of the illuminator mounted on a lighted flashlight shown in FIGS. 1,2. The distance to the object is estimated (even if inside a hole or recess), so the magnifier focus may be preset to the correct distance using the distance scale on the movable eyepiece in FIG. 4. The eyepiece housing is pulled out or pushed into the objective housing until the distance scale mark (on the eyepiece housing) for the desired distance is even with the top edge of the objective housing.

The telescopic magnifier is then placed over the illuminator eyepiece and is held snugly in place by tightening the thumbscrew on the objective housing. The object to view will then be prefocused for viewing through the magnifier eyepiece. 

I claim:
 1. A viewing accessory for use with a nonphotographic flashlight, to provide coaxial illumination, consisting of:
 2. The viewing accessory of claim 1 having a tubular housing with an open end and a closed end, said open end having a gripper means therein for removable attachment of the accessory to said flashlight.
 3. The viewing accessory of claim 1 having a mirror with a central hole mounted at a fixed angle within said housing, positioned to reflect a focused beam of light from said flashlight onto object being viewed.
 4. The viewing accessory of claim 1 with a viewing lens means or window on said housing, positioned to receive light transmitted through hole in said mirror from the object being viewed.
 5. The viewing accessory of claim 1 having an opening in said housing, opposite said lens means or window, through which light is directed for illumination of the viewed object, and coaxially reflected back through the hole in said mirror to said lens means or window.
 2. A removable companion telescopic magnifier to be used with the coaxial illuminator for flashlights of claim 1, in lieu of a lens means that is part of the eyepiece, to focus the viewed object at various distances from the said coaxial illuminator, and consists of
 1. The companion telescopic magnifier of claim 2 with a body consisting of two opaque movable telescoping housings.
 2. The companion telescopic magnifier of claim 2 with a lens means in each movable housing that forms a focusable magnifying telescope to view objects at various distances from the illuminator. 